[RFC][PATCH 41/42] allow link_path_walk() to take ERR_PTR()

[Al Viro]

From: Al Viro <v...@zeniv.linux.org.uk>

There is a check for IS_ERR(name) immediately upstream of each call
of link_path_walk(name, nd), with positives treated as if link_path_walk()
failed with PTR_ERR(name).  Taking that check into link_path_walk() itself
simplifies things nicely.

Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
---
 fs/namei.c | 38 +++++---------------------------------
 1 file changed, 5 insertions(+), 33 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index a9a2a8ac8b9d..a55da43f169c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2028,6 +2028,8 @@ static int link_path_walk(const char *name, struct 
nameidata *nd)
 {
        int err;
 
+       if (IS_ERR(name))
+               return PTR_ERR(name);
        while (*name=='/')
                name++;
        if (!*name)
@@ -2265,12 +2267,7 @@ static int path_lookupat(struct nameidata *nd, unsigned 
flags, struct path *path
        const char *s = path_init(nd, flags);
        int err;
 
-       if (IS_ERR(s)) {
-               terminate_walk(nd);
-               return PTR_ERR(s);
-       }
-
-       if (unlikely(flags & LOOKUP_DOWN)) {
+       if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) {
                err = handle_lookup_down(nd);
                if (unlikely(err < 0)) {
                        terminate_walk(nd);
@@ -2281,10 +2278,6 @@ static int path_lookupat(struct nameidata *nd, unsigned 
flags, struct path *path
        while (!(err = link_path_walk(s, nd))
                && ((err = lookup_last(nd)) > 0)) {
                s = trailing_symlink(nd);
-               if (IS_ERR(s)) {
-                       err = PTR_ERR(s);
-                       break;
-               }
        }
        if (!err)
                err = complete_walk(nd);
@@ -2331,12 +2324,7 @@ static int path_parentat(struct nameidata *nd, unsigned 
flags,
                                struct path *parent)
 {
        const char *s = path_init(nd, flags);
-       int err;
-       if (IS_ERR(s)) {
-               terminate_walk(nd);
-               return PTR_ERR(s);
-       }
-       err = link_path_walk(s, nd);
+       int err = link_path_walk(s, nd);
        if (!err)
                err = complete_walk(nd);
        if (!err) {
@@ -2663,17 +2651,10 @@ path_mountpoint(struct nameidata *nd, unsigned flags, 
struct path *path)
 {
        const char *s = path_init(nd, flags);
        int err;
-       if (IS_ERR(s)) {
-               terminate_walk(nd);
-               return PTR_ERR(s);
-       }
+
        while (!(err = link_path_walk(s, nd)) &&
                (err = mountpoint_last(nd)) > 0) {
                s = trailing_symlink(nd);
-               if (IS_ERR(s)) {
-                       err = PTR_ERR(s);
-                       break;
-               }
        }
        if (!err) {
                *path = nd->path;
@@ -3512,19 +3493,10 @@ static struct file *path_openat(struct nameidata *nd,
        }
 
        s = path_init(nd, flags);
-       if (IS_ERR(s)) {
-               terminate_walk(nd);
-               fput(file);
-               return ERR_CAST(s);
-       }
        while (!(error = link_path_walk(s, nd)) &&
                (error = do_last(nd, file, op)) > 0) {
                nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
                s = trailing_symlink(nd);
-               if (IS_ERR(s)) {
-                       error = PTR_ERR(s);
-                       break;
-               }
        }
        terminate_walk(nd);
 out2:
-- 
2.11.0